2 * Copyright (c) 2013 David Chisnall
5 * This software was developed by SRI International and the University of
6 * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
7 * ("CTSRD"), as part of the DARPA CRASH research programme.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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43 * The dtb namespace contains code related to the generation of device tree
44 * blobs, the binary representation of flattened device trees. The abstract
45 * tree representation calls into this code to generate the output.
49 /** The token types in the DTB, as defined by ยง7.4.1 of the ePAPR
50 * specification. All of these values are written in big-endian format in the
56 * Marker indicating the start of a node in the tree. This is followed
57 * by the nul-terminated name. If a unit address is specified, then
58 * the name also contains the address, with an @ symbol between the end
59 * of the name and the start of the address.
61 * The name is then padded such that the next token begins on a 4-byte
62 * boundary. The node may contain properties, other nodes, both, or be
65 FDT_BEGIN_NODE = 0x00000001,
67 * Marker indicating the end of a node.
69 FDT_END_NODE = 0x00000002,
71 * The start of a property. This is followed by two 32-bit big-endian
72 * values. The first indicates the length of the property value, the
73 * second its index in the strings table. It is then followed by the
74 * property value, if the value is of non-zero length.
76 FDT_PROP = 0x00000003,
78 * Ignored token. May be used for padding inside DTB nodes.
82 * Marker indicating the end of the tree.
88 * Returns the token as a string. This is used for debugging and for printing
89 * human-friendly error messages about malformed DTB input.
91 inline const char *token_type_name(token_type t)
96 return "FDT_BEGIN_NODE";
98 return "FDT_END_NODE";
110 * Abstract class for writing a section of the output. We create one
111 * of these for each section that needs to be written. It is intended to build
112 * a temporary buffer of the output in memory and then write it to a file
113 * stream. The size can be returned after all of the data has been written
114 * into the internal buffer, so the sizes of the three tables can be calculated
115 * before storing them in the buffer.
120 * Writes a label into the output stream. This is only applicable for
121 * assembly output, where the labels become symbols that can be
122 * resolved at link time.
124 virtual void write_label(string name) = 0;
126 * Writes a comment into the output stream. Useful only when debugging
129 virtual void write_comment(string name) = 0;
131 * Writes a string. A nul terminator is implicitly added.
133 virtual void write_string(string name) = 0;
135 * Writes a single 8-bit value.
137 virtual void write_data(uint8_t) = 0;
139 * Writes a single 32-bit value. The value is written in big-endian
140 * format, but should be passed in the host's native endian.
142 virtual void write_data(uint32_t) = 0;
144 * Writes a single 64-bit value. The value is written in big-endian
145 * format, but should be passed in the host's native endian.
147 virtual void write_data(uint64_t) = 0;
149 * Writes the collected output to the specified file descriptor.
151 virtual void write_to_file(int fd) = 0;
153 * Returns the number of bytes.
155 virtual uint32_t size() = 0;
157 * Helper for writing tokens to the output stream. This writes a
158 * comment above the token describing its value, for easier debugging
161 inline void write_token(token_type t)
163 write_comment(token_type_name(t));
164 write_data((uint32_t)t);
167 * Helper function that writes a byte buffer to the output, one byte at
170 void write_data(byte_buffer b);
174 * Binary file writer. This class is responsible for writing the DTB output
175 * directly in blob format.
177 class binary_writer : public output_writer
180 * The internal buffer used to store the blob while it is being
186 * The binary format does not support labels, so this method
189 virtual void write_label(string) {}
191 * Comments are ignored by the binary writer.
193 virtual void write_comment(string) {}
194 virtual void write_string(string name);
195 virtual void write_data(uint8_t v);
196 virtual void write_data(uint32_t v);
197 virtual void write_data(uint64_t v);
198 virtual void write_to_file(int fd);
199 virtual uint32_t size();
202 * Assembly writer. This class is responsible for writing the output in an
203 * assembly format that is suitable for linking into a kernel, loader, and so
206 class asm_writer : public output_writer
209 * The internal buffer for temporary values. Note that this actually
210 * contains ASCII text, but it is a byte buffer so that we can just
211 * copy strings across as-is.
215 * The number of bytes written to the current line. This is used to
216 * allow line wrapping, where we aim to write four .byte directives to
217 * make the alignment clearer.
221 * The current number of bytes written. This is the number in binary
222 * format, not the number of bytes in the buffer.
224 uint32_t bytes_written;
227 * Writes a C string directly to the output as-is. This is mainly used
228 * for writing directives.
230 void write_string(const char *c);
232 * Writes the string, starting on a new line.
234 void write_line(const char *c);
236 * Writes a byte in binary format. This will emit a single .byte
237 * directive, with up to four per line.
239 void write_byte(uint8_t b);
241 asm_writer() : byte_count(0), bytes_written(0) {}
242 virtual void write_label(string name);
243 virtual void write_comment(string name);
244 virtual void write_string(string name);
245 virtual void write_data(uint8_t v);
246 virtual void write_data(uint32_t v);
247 virtual void write_data(uint64_t v);
248 virtual void write_to_file(int fd);
249 virtual uint32_t size();
253 * Class encapsulating the device tree blob header. This class stores all of
254 * the values found in the header and is responsible for writing them to the
260 * Magic value, used to validate that this really is a device tree
261 * blob. Should always be set to 0xd00dfeed.
265 * The total size of the blob, including header, reservations, strings
266 * table, and padding.
270 * The offset from the start of the blob of the struct table (i.e. the
271 * part of the blob containing the entire device tree).
273 uint32_t off_dt_struct;
275 * The offset from the start of the blob of the strings table.
277 uint32_t off_dt_strings;
279 * The offset of the reservation map from the start of the blob.
281 uint32_t off_mem_rsvmap;
283 * The version of the blob. This should always be 17.
287 * The earliest version of the DTB specification with which this blob
288 * is backwards compatible. This should always be 16.
290 uint32_t last_comp_version;
292 * The ID of the CPU where this boots.
294 uint32_t boot_cpuid_phys;
296 * The size of the strings table.
298 uint32_t size_dt_strings;
300 * The size of the struct table.
302 uint32_t size_dt_struct;
304 * Writes the entire header to the specified output buffer.
306 void write(output_writer &out);
308 * Reads the header from bits binary representation in a blob.
310 bool read_dtb(input_buffer &input);
312 * Default constructor. Initialises the values that have sensible
313 * defaults, leaves the others blank.
315 header() : magic(0xd00dfeed), version(17), last_comp_version(16),
316 boot_cpuid_phys(0) {}
320 * Class encapsulating the string table. FDT strings are stored in a string
321 * section. This maintains a map from strings to their offsets in the strings
324 * Note: We don't currently do suffix matching, which may save a small amount
329 * Map from strings to their offset.
331 std::map<string, uint32_t> string_offsets;
333 * The strings, in the order in which they should be written to the
334 * output. The order must be stable - adding another string must not
335 * change the offset of any that we have already referenced - and so we
336 * simply write the strings in the order that they are passed.
338 std::vector<string> strings;
340 * The current size of the strings section.
345 * Default constructor, creates an empty strings table.
347 string_table() : size(0) {}
349 * Adds a string to the table, returning the offset from the start
350 * where it will be written. If the string is already present, this
351 * will return its existing offset, otherwise it will return a new
354 uint32_t add_string(string str);
356 * Writes the strings table to the specified output.
358 void write(dtb::output_writer &writer);